Transmission of hepatitis B virus (HBV) from mother to infant
during the perinatal period represents one of the most efficient
modes
of HBV infection and often leads to severe long-term sequelae.
Infants
born to mothers positive for hepatitis B surface antigen (HBsAg)
and
hepatitis B "e" antigen (HBeAg) have a 70%-90% chance of acquiring
perinatal HBV infection, and 85%-90% of infected infants will
become
chronic HBV carriers (1,2). It has been estimated that more than
25%
of these carriers will die from primary hepatocellular carcinoma
or
cirrhosis of the liver (3). These deaths usually occur during
adulthood, when familial and financial responsibilities make them
particularly devastating. In the United States, an estimated
16,500
births occur to HBsAg-positive women each year (about 4,300 of
whom
are also HBeAg- positive), and approximately 3,500 of these
infants
become chronic HBV carriers. Prenatal screening of all pregnant
women
would identify those who are HBsAg- positive and thus would allow
treatment of their newborns with hepatitis B immune globulin
(HBIG)
and hepatitis B (HB) vaccine, a regimen that is 85%-95% effective
in
preventing the development of the HBV chronic carrier state
(2,4-6).

In 1984, the Immunization Practices Advisory Committee (ACIP)
recommended that pregnant women in certain groups at high risk for
HBV
infection be screened for HBsAg during a prenatal visit and, if
found
to be HBsAg-positive, that their newborns receive HBIG and HB
vaccine
at birth (7). No data are available regarding the proportion of
high-risk women currently being screened in clinical practice, but
several studies and the experience of public health workers
indicate
that major problems have been encountered in implementing these
recommendations (8-12). These include 1) concerns about the
sensitivity, specificity, and practicality of the current ACIP
guidelines for identifying HBV carrier mothers; 2) lack of
knowledge
among prenatal health-care providers about the risks of perinatal
transmission of HBV and about recommended screening and treatment
procedures; 3) poor coordination among medical-care workers who
provide treatment and follow-up of mothers and infants; and 4)
refusal
of some public and private third-party payers to reimburse for HBV
screening of pregnant women and treatment of their infants. In
addition, concern has been expressed that these recommendations
may
not be practical or applicable in some U.S. jurisdictions where
HBV
infection is highly endemic, such as parts of Alaska and certain
Pacific Islands.

The problems encountered in implementing the currently
recommended
strategy of screening high-risk women have been examined by a
number
of investigators. Recent studies in several large inner-city
hospitals, where all pregnant women were tested for HBsAg, have
found
that only about 35%-65% of HBsAg-positive mothers would have been
identified by following the current ACIP guidelines (8-12). In
these
studies, the prevalence of HBsAg in inner-city black (0.4%-1.5%)
and
Hispanic women was higher than expected. Several investigators
expressed concern that many health-care providers are too busy or
may
be reluctant to obtain the sexual and drug-use history necessary
to
identify high-risk patients for screening. In addition, persons
providing health care to pregnant women often are not aware of the
risks of perinatal transmission of HBV and of the recommended
screening and treatment guidelines. In one study, 40% of
obstetricians
could name no more than two groups at high risk for HBV infection,
and
only 28% knew the recommended treatment for infants born to HBV
carrier mothers (CDC, unpublished data).

Given these limitations, it is now evident that routine
screening
of all pregnant women is the only strategy that will provide
acceptable control of perinatal transmission of HBV infection in
the
United States. Screening the approximately 3.5 million pregnant
women
per year for HBsAg would identify 16,500 positive women and allow
treatment that would prevent about 3,500 infants from becoming HBV
carriers. Recent studies also indicate that the costs and benefits
of
universal testing of mothers are comparable to those encountered
in
other widely implemented programs of prenatal and blood-donor
screening (13,14). The cost of an HBsAg test ranges from an
estimated
$3.50 per test in blood-bank laboratories to $21.00 per test in
private commercial laboratories. If one assumes an average
screening
cost ranging from $12.00 to $20.00 per test plus $150.00 for the
HBIG
and vaccine needed to treat each infant of an HBsAg-positive
mother,
the cost to prevent one newborn infant from becoming a chronic HBV
carrier would be between $12,700 and $20,700.

HBsAg testing should be done early in pregnancy when other
routine
prenatal testing is done. The HBsAg test is widely available and
can
be added to the routine prenatal "panel" of tests without
requiring
additional patient visits. The advantages of making HBsAg testing
routine during early pregnancy include 1) the ability to identify
HBV
carrier mothers that is not dependent on the health-care
provider's
identifying high-risk women or ordering HBsAg as a special test;
2)
the availability of test results before delivery so that infants
can
receive HBIG and vaccine without delay after birth; and 3)
appropriate
counseling of families before delivery (15).

Because more than 90% of women found to be HBsAg-positive on
routine screening will be HBV carriers, routine follow-up testing
later in pregnancy is not necessary for the purpose of screening.
In
special situations, such as when the mother is thought to have
acute
hepatitis, when there has been a history of exposure to hepatitis,
or
when particularly high-risk behavior such as parenteral drug abuse
has
occurred during the pregnancy, an additional HBsAg test can be
ordered
during the third trimester. Few women in populations at low risk
for
HBV infection will have a change in HBsAg status during subsequent
pregnancies. However, because of the expected benefits of making
HBsAg
testing a routine part of each prenatal panel, testing should be
done
during each pregnancy.

Women who present for delivery without prenatal care or
without
medical records documenting the results of HBsAg screening should
have
the HBsAg test done as soon as possible after admission, since
delay
in administration of HBIG to infants of carrier mothers will
decrease
the efficacy of therapy. In the studies that demonstrated the
highest
efficacy (85%-95%) of combined HBIG and HB vaccine prophylaxis,
HBIG
was administered within 2-12 hours after birth (2,4-6). In one
study
in which only HBIG was used for prophylaxis, no efficacy was found
if
HBIG was given more than 7 days after birth, and a significant
decrease in efficacy was observed if it was given more than 48
hours
after birth (16). Only one-third of U.S. hospitals currently
perform
the HBsAg test as an in-house procedure, and many of these have
technicians who are trained to do the test available on only one
shift. Hospitals that cannot rapidly test for HBsAg should either
develop this capability or arrange for testing to be done at a
local
laboratory or blood bank where test results can be obtained within
24
hours.

The commercially available HBsAg tests have an extremely high
sensitivity and specificity if positive tests are repeated and
confirmed by neutralization as recommended by the manufacturers of
the
reagent kits. Testing for other markers of HBV infection, such as
HBeAg, is not necessary for maternal screening. Mothers who are
positive for both HBsAg and HBeAg have the highest likelihood of
transmitting HBV to their newborns. However, infants of mothers
who
are HBsAg-positive but HBeAg- negative may become infected and
develop
severe, even fatal, fulminant hepatitis B during infancy (17,18).
For
this reason, HBIG and HB vaccine treatment of all babies born to
HBsAg-positive women is recommended.

HBsAg-positive mothers identified during screening may have
HBV-related acute or chronic liver disease and should be evaluated
by
a physician. Identification of women who are HBV carriers through
prenatal screening presents an opportunity to vaccinate
susceptible
household members and sexual partners of HBV carriers, as
previously
recommended (19). Screening and vaccination of susceptible
contacts
should be done by the family's pediatrician, primary health-care
provider, or the physician evaluating the clinical status of the
HBsAg-positive pregnant women.

Implementation of the recommendations to prevent perinatal
transmission requires maternal screening, treatment of the newborn
in
the hospital, and administration of subsequent doses of HB vaccine
to
the infant during pediatric visits at 1 and 6 months of age. This
multistep process requires effective transfer of information among
several groups of health-care providers, knowledge of recommended
treatment, and availability of HBIG and vaccine at separate
facilities. Treatment failures due to lack of communication among
health-care providers can occur, especially in situations where
prenatal, obstetric, and pediatric care are provided in different
facilities (20). Central coordination of the treatment of these
infants by city, county, or state health departments would improve
the
education of the health-care providers involved and increase the
likelihood that proper treatment is provided.

In certain populations under U.S. jurisdiction, including
Alaskan
Natives and Pacific Islanders, as well as in many other parts of
the
world, HBV infection is highly endemic in the general population,
and
transmission occurs primarily during childhood (21). In such
groups,
universal vaccination of newborns with HB vaccine is recommended
to
prevent disease transmission both during the perinatal period and
during childhood. Several studies have shown that HB vaccine given
without HBIG will prevent 70%-85% of perinatal HBV infections and
95%
of early childhood infections (22,23). In many of these areas with
highly endemic HBV infection, prenatal screening is impractical
because the population is isolated, laboratory facilities are not
available, and/or health-care budgets and personnel are limited.
In
these areas, control of HBV infection can be better achieved by
directing available resources into programs to vaccinate all
children
with HB vaccine. Programs for screening all mothers for HBsAg and
providing HBIG to infants born to carrier mothers are costly and
will
add only modestly to disease prevention. They should be considered
only after the program for universal vaccination of children has
been
implemented.

RECOMMENDATIONS

All pregnant women should be routinely tested for HBsAg during
an
early prenatal visit in each pregnancy. This testing should be
done at
the same time that other routine prenatal screening tests are
ordered.
In special situations, such as when acute hepatitis is suspected,
when
there has been a history of exposure to hepatitis, or when the
mother
has a particularly high-risk behavior such as intravenous drug
abuse,
an additional HBsAg test can be ordered later in the pregnancy.

If a woman has not been screened prenatally or if test results
are
not available at the time of admission for delivery, HBsAg testing
should be done at the time of admission, or as soon as possible
thereafter. If the mother is identified as HBsAg- positive more
than 1
month after giving birth, the infant should first be tested for
HBsAg;
if negative, the infant should be treated with HBIG and HB
vaccine.
Hospitals where infants are delivered should have HBsAg testing
capabilities or should be able to obtain HBsAg results within 24
hours
from a local laboratory.

If a serum specimen is positive for HBsAg, the same specimen
should be tested again, and then the test results should be
confirmed
by neutralization. It is unnecessary to test for other HBV markers
during maternal screening, although HBsAg- positive mothers
identified
during screening may have HBV-related acute or chronic liver
disease
and should be evaluated by their physician.

Infants born to HBsAg-positive mothers should receive HBIG
(0.5
mL) intramuscularly (IM) once they are physiologically stable,
preferably within 12 hours after birth. HB vaccine, either
plasma-derived (10 *gmg per dose) or recombinant (5 *gmg per
dose),
should be administered IM in three doses of 0.5 mL each. The first
dose should be given concurrently with HBIG but at a different
site.
If vaccine is not immediately available, the first dose can be
given
within 7 days after birth. The second and third doses should be
given
1 month and 6 months after the first. Testing the infant for HBsAg
and
its antibody (anti-HBs) is recommended at 12-15 months of age to
monitor the effectiveness of therapy. If HBsAg is not detectable
and
anti-HBs is present, the child can be considered protected.
Testing
for antibody to hepatitis B core antigen (anti-HBc) is not useful,
since maternal anti-HBc can persist for more than a year. HBIG and
HB
vaccination do not interfere with the routine childhood
immunizations.

Household members and sexual partners of HBV carriers
identified
through prenatal screening should be tested to determine
susceptibility to HBV infection and, if susceptible, should
receive HB
vaccine. Screening and vaccination of susceptible contacts should
be
done by the family's pediatrician, primary health-care provider,
or
the physician evaluating the clinical status of the HBsAg-positive
pregnant women.

Obstetric and pediatric staff should be notified directly
about
HBsAg-positive mothers so that the neonate can receive therapy
without
delay after birth and follow-up doses of vaccine can be given.
Hospitals, as well as state, county, and city health departments,
should establish programs to educate appropriate health-care
providers
about perinatal transmission of HBV and its control through
maternal
screening, treatment of infants, and vaccination of susceptible
household and sexual contacts of HBV carrier women.

Programs to coordinate the activities of those providing
prenatal
care, hospital- based obstetrical services, and pediatric
well-baby
care must be established to assure proper follow-up and treatment
of
infants born to HBsAg-positive mothers and other susceptible
household
and sexual contacts.

In populations under U.S. jurisdiction in which hepatitis B
infection is highly endemic, including certain Alaskan Native and
Pacific Island groups, vaccination of all newborns with HB vaccine
is
the most effective strategy for HB control. In these populations,
such
vaccination programs should be given highest priority. In areas
where
HBsAg screening of mothers and use of HBIG in infants born to HBV
carrier mothers are not practical, the vaccination of all newborns
with HB vaccine should be considered the appropriate treatment.
Editorial Note: Hepatitis B vaccine is the first human vaccine
that
can prevent both serious chronic disease and a uniformly fatal
type of
cancer. These recommendations, developed in consultation with
representatives of the American College of Obstetricians and
Gynecologists and the American Academy of Pediatrics, represent a
major step toward control of perinatal hepatitis B transmission in
the
United States. Programs for universal screening of pregnant women
are
currently in progress in Hawaii, certain Canadian provinces,
Italy,
West Germany, New Zealand, Australia, and Japan. More extensive
infant
HB vaccination programs are in progress in Alaska, American Samoa,
Korea, Taiwan, Singapore, and the People's Republic of China. A
number
of U.S. health-care facilities have already begun to screen all
pregnant women for HBsAg.

State and local health departments can facilitate
implementation
of these recommendations by 1) working to assure that all women
receiving prenatal care in both public and private sector programs
are
offered screening and appropriate treatment; 2) working to assure
that
costs of screening and treatment are covered by public and private
third-party payers; 3) establishing programs to coordinate the
transfer of information between prenatal, obstetric, and pediatric
health-care providers; and 4) providing health education about
hepatitis B to the public and to health-care providers. CDC will
continue to work with state and local health agencies and
professional
associations in hepatitis B prevention and control.
References

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